Rotor slide-type pump with rotor of free-floating segments



Dec. 12, 1961 c. F. HIGH ROTOR SLIDE-TYPE PUMP WITH ROTOR OF FREE-FLOATING SEGMENTS 2 Sheets-Sheet 1 Filed Aug. 4, 1958 35 i 3 INVENTOR.

CARL F.HIGH MTW ATTORNEYS Dec. 12, 1961 F. HIGH 3,012,515

ROTOR SLIDE- E P WITH ROTOR OF FREE-FLOAT SEGMENTS Filed Aug. 4, 1958 2 Sheets-Sheet 2 i.) 45 4s F|G.5.

ATTORNEYS United States Patent 3,012,515 ROTOR SLIDE-TYPE PUMP WITH ROTOR 0F FREE-FLOATING SEGMENTS Carl F. High, Detroit, Mich., assignor to Borg-Warner Corporation, Chicago, 111., a corporation of Illinois Filed Aug. 4, 1958, Ser. No. 753,029 9 Claims. (Cl. 103-160) My invention relates to fuel pumps and more particularly to an improved small capacity gear pump of the rotor slide type.

In the development of pumps for supplying gasoline and similar low viscosity fuels under pressure to internal combustion engines, inherent weaknesses have been encountered in the design of gear and vane pumps, resulting in either inferior performance or in the deterioration of the pump components resulting in too short a life for practical widespread use.

In considering the gear pump; the machining accuracy required to maintain the pitch-diameter and concentricity of the gears, the exact center distances between gears, and the end clearances and outside clearance in the pump body, make the pumps extremely sensitive to build. With the necessity of delivering fluids under high pressure, the overloading of the inside diameter and the pin of the idling gear, is a serious wear problem. When wear occurs in the gear hearing or on the pin, the gear moves outward and contacts the bore in the housing which permits gear teeth to cut away the housing and cause leakage. Because of wear, such gear pumps have had to be designed for overcapacity so that the time would be extended before they failed to prime themselves or deliver sufficient fuel for engine needs.

The vane pump, which superceded the gear pump, was an improvement, but it cost more to produce and although springs urging the vanes outward overcame the bore clearance problem, the end-clearance defect remained unsolved. Wear of the pump bore, caused by the springs urging the vanes outward, was a new problem, as was the problem of vane sticking. Vane sticking could be eliminated by fitting the vanes more loosely, but then leakage around the vanes would increase. When the vanes were fitted closely enough to produce acceptable pumping efiiciency, the vanes would stick more easily, especially at reduced temperatures. As with the gear pumps, wear lowered the pumping efficiency and life expectancy to a point where the pump either failed to prime itself or to deliver a suflicient quantity of fuel at the required pressure to meet fuel requirements. r

The present pump is of the type of rotor-slide pump which was developed in attempting to overcome the difliculties of the gear and vane pumps, such pumps generally comprising a slide or piston rotatable eccentrically in a pumping chamber in such a way as to reciprocate relative to the chamber. These pumps presented new problems which the present construction is intended to overcome, particularly the problem of side loading on the eccentrically mounted pin which determined the stroke of the piston which in turn determined the capacity of the pump. In searching for a means to render the rotorslide pump constant in efliciency over a long period of time; that is, to build a high pressure fuel-supply pump which would not wear out over an extremely long period of time, the present pump was conceived in which, briefly, the drive shaft is located eccentric to the pumping chamber and is extended completely across the chamber, the pumping elements whirling in the chamber which becomes the main bearing. The success of the present arrangement is assured by manufacturing the pumping elements preferably of a sintered material having a very low coeflicient of friction. Low cost is achieved by producing the parts to precise dimension by the powder metallurgy and sintering process of low friction material.

An object of the present invention is to eliminate problems inherent in fluid pumps by constructing a small capacity rotor-slide fluid pump capable of delivering fluid at a substantially high pressure and operable continuously over extended period of time without appreciable wear.

Another object of the invention is to improve fluid pumps by providing simplified standardized interchangeable elements capable of assembly in a variety of units.

A further object of the invention is to improve fluid pumps by providing a combination of elements operable under the action of the fluid pressure to adjust for wear and seal the fluid inlet from the outlet.

For a more complete understanding of the invention, reference may be had to the accompanying drawings illustrating two preferred embodiments of the invention in which like reference characters refer to like parts throughout the several views and in which FIG. 1 is a longitudinal cross-sectional view of one preferred pump embodying the present invention.

FIG. 2 is a cross-sectional view of the pump taken substantially on the line 2-2 of FIG. 1.

FIG. 2A, 2B and 2C are cross sectional views like FIG. 2 but illustrating other operating positions of the pumping elements.

FIG. 3 is a cross-sectional view of the pump taken substantially on the line 33 of FIG. 1.

FIG. 4 is a longitudinal cross-sectional view taken substantially on the line 4-4 of FIG. 2.

FIG. 5 is a longitudinal cross-sectional view of another preferred pump embodying the present invention; and

FIG. 6 is a cross-sectional view taken substantially on the line 6-6 of FIG. 5.

Referring to FIGS. 1 through 4, a preferred pump 10 comprises a housing structure 11 having a cylindrical pumping chamber 12 closed at the outer end by an end plate 13 and a cover 14 secured to the housing by screws 15 or other means with the end plate 13 accurately positioned by any means such as pins 16. An inlet port 17 and an outlet port 18 are open to arcuate inlet and outlet recesses 19 and 20 respectively disposed on opposite sides of the cylindrical chamber 12 as shown.

A drive shaft 25 is rotatably carried in a bore 26 extending through the housing 11 to the chamber 12 and is disposed eccentrically to the chamber on an axis P extending parallel with an offset from the chamber axis C, as indicated in FIGS. 2 and 3. A pumping slideor piston 27 is disposed in the chamber 12 and comprises end pol;

tions 27a connected by an intermediate bridge portion 27b. The chamber end of the shaft 25 is provided with fork portions 28 which straddle the bridge 27b. The'fork ends are carried in a bear-ing element 29 which rotates in a recess 30 provided in the end plate 13, the recess 30 being eccentric to the chamber 12 as is the bore 26; Sufficient space is provided between the forks 28 to permit lateral reciprocating motion of the piston 27 relative to the shaft 25 as the piston rotates. p

Between the straight sides of the piston 27 and" the peripheral wall of the chamber 12 are fitted a pair of separate, floating arcuate segments 35 which rotate freely on the axis C as the piston rotates on the axis P. Due to the eccentricity of the drive shaft 25 relative to the chamber 12, the piston 27 in rotation reciprocates laterally relative to the segments 35, such that the spaces between the ends of the piston 27 and the peripheral wall of the chamber 12 are alternately expanded and contracted in volume. As illustrated in the successive operating positions of FIGS. 2, 2A, 2B and 20, one such space is in the process of contracting as it opens to the outlet recess 20 While the other space is in the process of expanding as it opens to the inlet recess 19, there being a very small moment during which the arcuate segments 35 completely close the recesses 19 and 20 for preventing backflow of pressure, as in the position of FIG. 2. The directional arrows in FIGS. 2, 2A, 2B and 2C indicate the direction of rotation of the piston 27 and segments 35. FIG. 2 illustrates the initial position of a stroke, FIG. 2A illustrates a /4 stroke position, FIG. 28 a /2 stroke position, and FIG. 2C a /4 stroke position, after which the piston 27 has reversed end for end to the position of FIG. 2 for another stroke. Thus one cycle of operation would comprise two pressure strokes.

The inner peripheral wall of the chamber 12 provides a bearing surface for the segments 35. Since the segments 35 are freely floating in the chamber 12, fluid pressure at the outlet side and in the compressing end space will thrust them alternately toward the inlet side of the chamber 12, providing an effective seal against fluid leakage across the chamber from the outlet to the inlet, even after the parts have become worn on the periphery. The piston 27 and segments 35 ride on the end plate 13.

A floating end plate 36 is fitted over the shaft 25 and within the chamber 12, being urged against the piston 27 and segments 35 by a spring 37 which bears on a face seal 38, providing an effective shaft seal and automatically compensating for any end wear of the piston 27 and segments '35. A dog point screw 39, shown in FIG. 4, prevents the end plate 36 from rotating in the chamber 12.

FIGS. and 6 illustrate an embodiment of the invention in an immersion type of fluid supply pump, in which a pump housing 45 is secured into the end of a motor housing 46 and has a pump chamber 47, an inlet recess 48, an outlet recess 49, a piston 50, and piston segments 51 similar to the parts shown in FIGS. 1 through 4. However, the fork members 52 are connected at the inboard end by a plate 53 and an inboard bearing element 53a which is driven from the end of the drive shaft 54 of a motor 55. The outboard ends of the forks 52 are similarly connected by a plate 56 and an outboard bearing element 57 which is carried in a recess 58 provided in an end plate 59 having an inlet channel 60 connected by suitable passages 61 with the inlet recess 48. The outlet recess 49 is connected by suitable passages 62 with the interior of the motor housing 46. This construction requires no seal as in the pump to prevent fuel leakage, and in place of a seal, the floating end plate 63 is urged against the piston 50 and segments 51 by a spring 64 having its other end bearing on the inner part of the housing 45.

Fuel flow is from the inlet recess 48 as pressurized by the piston 50 in the manner previously described, through the outlet recess 49, the passage 62 and the interior of the motor housing 46, to discharge through an outlet connection 65.

Although I' have described only two preferred embodiments of my invention, it will be apparent to one skilled in the art to which the invention pertains that various changes and modifications may be made therein without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. A fluid pump comprising a housing provided with a cylindrical pumping chamber and an intake and outlet open to laterally opposite sides of said chamber, a pumping piston disposed in said chamber and rotatable on an axis parallel with and offset from the axis of said chamber whereby said piston rotates eccentrically with respect to said chamber, the length of said piston being less than the diameter of said pumping chamber to provide variable volume spaces between the ends of said piston and the peripheral wall of said chamber, and a pair of free floating arcuate segments disposed on opposite sides of said piston and fitting closely between same and said peripheral wall of said chamber, said arcuate segments being rotated in said chamber with and by said piston, said piston reciprocating relative to said segments to alternately compress and expand the spaces between the ends of said piston and said chamber peripheral wall, and means rotating said piston.

2. The pump as defined in claim 1 and in which the arcuate surfaces of said segments are contoured to the radius of said chamber, the peripheral wall of said chamber serving as the bearing for said segments, said segments serving as fluid pressure barriers between said inlet and said outlet.

3. The pump as defined in claim 1 and in which the fluid being compressed by the piston urges said segments alternately into sealing engagement with said chamber wall adjacent said inlet opening.

4. The pump as defined in claim 1 and in which said housing has an end plate closing one end of said chamher, said piston and said segments rotatably sliding on said end plate.

5. The pump as defined in claim 4 and in which a drive shaft is connected to said piston and extends through said housing from the other end of said chamber.

6. The pump as defined in claim 5 and in which a floating end plate is disposed in said other end of said chamber and is slidable on said piston and segments, and means urging said floating end plate against said piston and segments to compensate for end clearance required due to expansion and wear of said piston and segments.

7. The pump as defined in claim 6 and in which said floating end plate has a peripheral edge closely fitting the peripheral Wall of said chamber and an inner hole closely fitting said drive shaft on the aforesaid offset axis, and means locking said floating end plate only against rotating motion.

8. The pump as defined in claim 5 and in which said piston comprises two end portions and an intermediate bridge portion, said drive shaft having a pair of spaced tines straddling said bridge portion and laterally spaced therefrom to permit relative sidewise reciprocation between said piston and said driveshatt in a direction normal to piston pumping motion.

9. The pump as defined in claim 8 and in which said end plate has a bearing recess, a bearing element disposed in said recess and engaged with the ends or" said tines for rotation therewith.

References Cited in the file of this patent UNITED STATES PATENTS 1,027,139 McGeorge May 21, 1912 1,671,565 Astrom May 29, 1928 1,713,417 Burrows May 14, 1929 2,134,153 Seyvertsen Oct. 25, 1938 2,684,038 Johnson July 20, 1954 

